Basis of Presentation	6 Months Ended
Mar. 29, 2015
Basis of Presentation
Basis of Presentation	1.Basis of Presentation The accompanying unaudited condensed consolidated financial statements and related notes of Tetra Tech, Inc. (“we,” “us” or “our”) have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. They do not include all of the information and footnotes required by GAAP for complete financial statements and, therefore, should be read in conjunction with the audited consolidated financial statements and related notes contained in our Annual Report on Form 10-K for the fiscal year ended September 28, 2014. These financial statements reflect all normal recurring adjustments that are considered necessary for a fair statement of our financial position, results of operations and cash flows for the interim periods presented. The results of operations and cash flows for any interim period are not necessarily indicative of results for the full year or for future years. Beginning in the first quarter of fiscal 2015, we reorganized our core operations to better align them with our markets, resulting in two renamed reportable segments. We now report our water resources, water and wastewater treatment, environment, and infrastructure engineering activities in the Water, Environment and Infrastructure (“WEI”) reportable segment. Our Resource Management and Energy (“RME”) reportable segment includes our oil and gas, energy, mining, waste management, remediation, utilities, and international development services. We report the results of the wind-down of our non-core construction activities in the Remediation and Construction Management (“RCM”) reportable segment. Prior year amounts for reportable segments have been revised to conform to the current-year presentation.

1.Basis of Presentation

The accompanying unaudited condensed consolidated financial statements and related notes of Tetra Tech, Inc. (“we,” “us” or “our”) have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. They do not include all of the information and footnotes required by GAAP for complete financial statements and, therefore, should be read in conjunction with the audited consolidated financial statements and related notes contained in our Annual Report on Form 10-K for the fiscal year ended September 28, 2014.

These financial statements reflect all normal recurring adjustments that are considered necessary for a fair statement of our financial position, results of operations and cash flows for the interim periods presented. The results of operations and cash flows for any interim period are not necessarily indicative of results for the full year or for future years.

Beginning in the first quarter of fiscal 2015, we reorganized our core operations to better align them with our markets, resulting in two renamed reportable segments. We now report our water resources, water and wastewater treatment, environment, and infrastructure engineering activities in the Water, Environment and Infrastructure (“WEI”) reportable segment. Our Resource Management and Energy (“RME”) reportable segment includes our oil and gas, energy, mining, waste management, remediation, utilities, and international development services. We report the results of the wind-down of our non-core construction activities in the Remediation and Construction Management (“RCM”) reportable segment. Prior year amounts for reportable segments have been revised to conform to the current-year presentation.